Methyl bromide package



June 16, 1959 A. E. DELINE METHYL BROMIDE PACKAGE Filed Nov. 15. 1957 INVENTOR.

ALBERT .E. DELINE ATTORNEY United States Patent METHYL BROMIDE PACKAGE Albert Deline, St. Louis, Michz, assignor to Michigan Chemical Corporation, St. Louis, Mich., a corporation of Michigan Application November 15, 1957,.Serial No. 696,823

3 Claims. (Cl. 206-84).

Thisinventionrelates to an improved package containing methyl bromide and more particularly toa sealed metal can containing methyl bromide.

Methyl bromide is widely usedfor the fumigation of. grain, soil fumigation, control of. poultry diseases and similar purposes. It is widely marketedthrough normaf commercial channels in sealed metal cans containingv a relatively small amount of the bromide on the order of one pound. The usual containeris a cylindrical metal can. having, aneck which tapers to a mouth'which is smaller in diameter than the main body of the can. The mouth of the can is sealed after the can-is substantially completely filled with the bromide by a gasketed'metal cap which is crimped around the upper edge of the neck.

Methyl bromide has a relatively. high. vapor pressure at ambient temperatures. Forexample, the: vapor pressure developed in a can of methyl bromide at 70 F. can rise as high as 60 pounds per square inch gauge and at 175" F. this pressure can rise to about IOU pounds per square inch. Due to this relatively high vapor pressure the gasket which, together with the metal cap, forms the closurev for the can must be made of a resilient material which provides a vapor-tight seal capable of'lioldi'ng a substantialiinternal vapor pressure;

Methyl bromide is an active solvent for many materials which are otherwise suitable for. gasket materials; It is particularly eifective in leaching the plasticizer out of plasticized gasketcompositions. The active solvent action, combined with the relatively high vapor pressure of this compound makes the packaging of this material, in economically feasible containers, a diflicult problem. Methyl bromide is highly toxic to man and animals. Any leakage of its containers creates a serious health hazard, as well as an economic waste arisingfrom the loss of the material itselfi The problem createdlhy the relatively'high' incidence of leaky containers has been a continuing. one since this compound has found commercial uses.

Now, it"is the. object'of' this. inventionito provide an economically feasible package of methyl bromide which can be made up by a rapid commercial filling and sealing operation, and which shows an extremely. low incidence of'leakage during transit andstorage, even at the relatively high ambient temperatures encountered in the tropics.

Other objects of this invention and its various advantageous features will become apparent as' this" description proceeds.

The packagein accordance with this invention comprises a metal can having a mouth of smallerdiameter than the body of: the can..itself,.a,body. of aliquid methyl bromide. within the metalcan, ametalcapcrimped withintandf around. the mouth :of: the said can, and a gasketof a. butadiene-acrylonitrile. co-pol-ymericelastomer positioned within. the metal. cap and against. the edges: ofthe mouth. of the. canto. provide a. vapor-tight sealfor the said mouth.

Although several features of this package contribute to the advantages which it provides, its most important featureis the gasket of a butadiene-acrylonitrile copolymer which provides the vapor-tight seal between the metal cap of the container and the edges" of the mouth of the main body of the container. This feature of the package is the result ofmy discovery of the surprising fact that of the various elastomers which ap eared to be possibilities for useas the gasket, the gasket of a butadiene acrylonitrile= co-polymer' proved itself to be the solution to the difiicult problem involved, both in actual service and under severe accelerated tests. This fact is quite surprising, in view of the fact that it has rounding the mouth of the can 1 and is un der; suffieient been authoritatively stated that a butadiene-acrylonitrile co-polymer. is not suitable for use as a gasket for halogenated solvents (Petroleum Processing, March 1957, page l 02;)f. It is also surprising in view of the fact that it did no't show up particularly well in comparative tests to determine the resistance of various elastomers to the action of the methyl bromide.

Thus, for example, determinations of the loss in weight 015 a series of polymerized butadiene-acrylonitrile gaskets, a series of plasticized polymerized Z-chlorobutadiene gaskets and a series of polyisobutylene gaskets upon immersion in methyl bromide for a period of 19 hours followed by air drying for 24 hours, gave the following average results:

Average percent loss in weight Polymerized- 2 chl'orobutadiene gaskets 26.0 Polymerized butadiene-acrylonitrile gaskets 13.0 Polyisobutylene gaskets 3.9

Polymerized 2-chlorobutadiene gaskets have been used for the sealing of methyl bromide cans on a commercial scale andhave proven to be unsatisfactory due to the high-percentage of leaky cans. Comparative service tests showed that polyisobutylene gaskets were unsatisfactory for the same reason, despite the fact that as indicated by the foregoing data, the gaskets are very slightly attacked by methylibromide. On the other hand, the polymerized butadiene-acrylonitrile gaskets have, as already noted, giveni excellent results both in accelerated leakage tests and in actual service tests.

Having now indicated the general nature of the package in accordance with this invention, I will now proceed with a. detailed descriptionof a preferred embodiment thereof with reference to the accompanying drawingin which the single figure is a vertical cross-sectional view of the package.

Referring to the drawing; the numeral 1, designates generally, a metal can adapted to withstand internal pres sure, which contains abody 2" of liquid methyl bromide. This can is' provided with a' metal cap 3* having 'a' cut gasket 4 made of a polymerized butadiene-acrylonitrile polymer.

The container 1 is comprised of a body section 5 and a neck section 6 both of which are drawn from sheet metal and seamless. The body section 5 actually has the shape of a hollow truncated cone, but is so slightly conical as to appear cylindrical upon casual inspection.

neck section 6' is irregulafly'tapered" to" a circular month which is surrounded by a rolled collar-like section -7.- The flatcircular section 8' of the cap'3 is surroundedby an upwardly extending-edge section-9 which is generally cylindricahbut which-isoutwardly crimped against the collar section 7 surrounding the mouth of the container. The section 9 continues-as'a section 10'which is approximately semi-circular and at its-outer edge is crimped. inwardly against the collar section 7 The gasket 4,.as indicated by the drawing, is positioned between the lower side of the-circular section lt) of the cap 3- andthe/upper edge of the collar section 8 surcompression force to cause the gasket to form a vaportight seal between the cap 3 and the can 1.

The can 1, has a circular, inwardly domed bottom section 12 which is aflixed to the lower edge of the conical body section 5 of the can by a rolled joint 13. The domed form of the bottom section 12 enables itto withstand internal pressure more effectively than if it were flat.

The efliciency of the package in accordance with this invention was proven by a series of tests in which it was compared with similar packages in which the flowed-in gasket of polymerized 2-chlorobutadiene and cut polyhad a flowed-in polymerized 2-chlorobutadiene gasket had definitely lost weight showing a definite leakage of the toxic methyl bromide.

In the foregoing test, as well as in the tests described hereinafter, the flowed-in polymerized Z-chlorobutadiene gaskets were used as a comparator for the cut polymerized acrylonitrile gasket forming an essential feature of the package in accordance with this invention, since the former type of gasket has had extensive commercial use as a part of methyl bromide packages.

Results of a series of similar long-term storage tests are summarized in Tables II and 111.

TABLE 11 Long term storage test at ambient temperature [Number of cans tested71] Temp. Number of mos.

Number of cans losing between- Gasket Polymerized butadlene-aerylonitrile Polymerized z-ehlorobutadiene Polymerlzed butadiene-aerylonitrlle. Polymerlzed 2-chlorobutadiene Polymerized butadiene-acrylonitril Polymerized 2-chlorobutadiene- Polymerized butadiene-aerylonitrile.

Polymertzed 2-chlorobutadiene Polymerized butadiene-acrylonitrile- Polymerized 2-chlorobutadlene Polymerized butadlene-acrylonitrlle Polymerlzed 2-chlorobutadiene QFOhONOOOOOOO HOOOHODUQOOO WDHQHOOCODOQ CHOP-000C000 TABLE III 125 F. storage test [Number of cans tested-6] Number of days Gasket Number of cans losing between- Polymerlzed butadiene-aerylonitrile... Polymerlzed 2-ch1orobutad1ene Polymerized butadiene-acrylonitrile-- Polymerized 2-chlorobutad1ene Polymerized butadiene-acry1onitri1e-. Polymerized 2-ehlorobutad1ene wowouao OOOOOO OOOOOO HOQQQO a temperature of 180 F. with the results shown in Table I.

TABLE I Packages heated to 180 F.

identical, except for the substitution of a flowed-in polymerized 2-chlorobutadiene gasket for the cut polymerized acrylonitn'le gasket 4, were stored for 72 days at room temperature, for 94 days at a temperature approximating 100 F. and finally, for 53 days at room temperature. At the end of this test it was found that none of the packages in accordance with this'invention had lost weight, while a total of 18 of the packages which In the foregoing tests which were conducted both under temperature conditions more extreme than the package is likely to encounter in use, and for long periods of time, the package in accordance with this invention showed no failures whatever, while in almost all the tests a significant number of the comparator packages failed.

Table IV summarizes the results of a series of comparative tests of methyl bromide packages in accordance with this invention which includes a cut gasket of a buta- Number 55 diene-acrylonitn'le co-polymer and of comparable pack- Number of Gasket a012, g 1 i 5 ages which utilize a polyisobutylene gasket.

p ages w c failed TABLE IV Long term storage test at ambient temperature Polymerlzed acrylonitrile 26 None 60 Polymerlzed z-chlorobutadiene- 44 12 Polylsobutylene s 3 Number Duration Number Percent Means of test, of cans rusted tested months rusted In the tests recorded by Table I, the packages which am 1 u But ene-acry onltr e failed lost their entire contents of methyl bromide. 5 copolymer gasket 216 14 9 L2 In another comparative test, 71 packages in accord- 'Polyisobutylene 12 11 9.2 ance with this invention and 70 packages which were The rusting of the cans recorded in Table IV, was in the vicinity of the junction of the caps and the top of the very slow leakage.

While I have described a preferred form of the package in accordance with this invention in detail, it will be understood that these details have been given for the purpose of fully illustrating the invention and that changes may be made in these details without departing from the spirit of my invention or the scope of the following claims. For example, instead of a conical, seamless body section, the can may have a cylindrical body section having a side seam. The neck section of the can may take a different form of taper. Again, the bottom of the can may be flat instead of inwardly domed.

I claim:

1. A package comprising a metal can having a main body section a mouth smaller than its main body section, a body of methyl bromide within the said main body section, a gasket of a polymeric butadiene-acrylonitrile elastomer positioned on the edge of the mouth of the can, a metal cap positioned over the said mouth and bearing forcefully on the gasket to place it under compression, and having edge sections extending downwardly around and forcefully bearing on the metal around the said mouth.

2. A package comprising a body of liquid methyl bromide within a metal can having a seamless side wall which has a body section comprised of a main body section which has the shape of a hollow truncated cone and an upper neck section which generally tapers to a circular month which is smaller than the main body section, an inwardly domed bottom afiixed to the lower edge of the main body section by a rolled joint, a gasket of a polymeric butadiene-acrylonitrile elastomer positioned on the edge of the said mouth, a circular metal cap positioned over the said mouth having an edge section which is generally semi-cylindrical in cross-section, which has an inner section which is outwardly crimped to bear forcefully against the inner side of the metal surround- 6 ing the said mouth, an outer section which is inwardly crimped to bear forcefully against the outer side of the metal surrounding the said mouth and an intermediate section which bears forcefully on the said gasket to place it under compression against the upper edge of the metal surrounding the mouth of the said can.

3. A package comprising a body of methyl bromide within a metal can having a seamless side wall which has a body section comprised of a main body section which has the shape of a hollow truncated cone and an upper section which generally tapers to a circular mouth which is smaller than the main body section and surrounded by a rolled section which is generally circular in vertical cross-section, an inwardly domed bottom aflixed to the lower edge of the main body section by a double rolled joint, a gasket of a polymeric butadiene-acrylonitrile elastomer position on the edge of the said mouth; a circular metal cap positioned over the said mouth having an edge section which is generally semi-cylindrical in cross-section, which has an inner section which is outwardly crimped to bear forcefully against the inner side of the metal surrounding the said month, an outer section which is inwardly crimped to bear forcefully against the outer side of the metal surrounding the said mouth and an intermediate section which bears forcefully on the said gasket to place it under compression against the upper edge of the metal surrounding the mouth of the said can.

References Cited in the file of this patent UNITED STATES PATENTS 2,117,180 Kronquest May 10, 1938 2,119,280 Kronquest et a1. May 31, 1938 2,626,073 Miller et a1. Jan. 20, 1953 2,728,475 Teeters et al. Dec. 27, 1955 

3. A PACKAGE COMPRISING A BODY OF METHYL BROMIDE WITHIN A METAL CAN HAVING A SEAMLESS SIDE WALL WHICH HAS A BODY SECTION COMPRISED OF A MAIN BODY SECTION WHICH HAS THE SHAPE OF A HOLLOW TRUNCATED CONE AND AN UPPER SECTION WHICH GENERALLY TAPERS TO A CIRCULAR MOUTH WHICH IS SMALLER THAN THE MAIN BODY SECTION AND SURROUNDED BY A ROLLED SECTION WHICH IS GENEARALLY CIRCULAR IN VERTICAL CROSS-SECTION, AN INWARDLY DOMED BOTTOM AFFIXED TO THE LOWER EDGE OF THE MAIN BODY SECTION BY A DOUBLE ROLLED JOINT, A GASKET OF A POLYMERIC BUTADIENE-ACRYLONITRILE ELASTOMER POSITION ON THE EDGE OF THE MOUTH; A CIRCULAR METAL CAP POSITIONED OVER THE SAID MOUTH HAVING AN EDGE SECTION WHICH IS GENERALLY SEMI-CYLINDRICAL IN CROSS-SECTION, WHICH HAS AN INNER SECTION WHICH IS OUTWARDLY CRIMPED TO BEAR FORCEFULLY AGAINST THE INNER SIDE OF THE METAL SURROUNDING THE SAID MOUTH, AN OUTER SECTION WHICH IS INWARDLY CRIMPED TO BEAR FORCEFULLY AGAINST THE OUTER SIDE OF THE METAL SURROUNDING THE SAID MOUTH AND AN IMMEDIATE SECTION WHICH BEARS FORCEFULLY ON THE SAID GASKET TO PLACE IT UNDER COMPRESSION AGAINST THE UPPER EDGE OF THE METAL SURROUNDING THE MOUTH OF THE SAID CAN. 